P1600: Immobilizer Signal Circuit Malfunction
Short answer: P1600 means “Immobilizer Signal Circuit Malfunction”. Below is what it means on each of the 2 cars we cover, with a link to the full page for each car.
P1600 on each car
| Car | Meaning on this car | Confidence |
|---|---|---|
| Toyota Passo (1st gen) | Immobilizer Signal Circuit Malfunction (P1600/83) | high |
| Toyota Vitz (1st gen) | Engine computer battery back-up circuit | medium |
Symptoms
- When the engine starts, the rolling code can not reading out or writing to the EFI ECU.
Likely causes
- EFI ECU
Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.